Foundry sandcore mold release composition

ABSTRACT

A release agent composition to facilitate separation of patterns and core boxes from foundry molds and cores comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, a catalyst, and a solvent or a hydroxy-terminated polyalkylsiloxane. Further is provided a method to improve the release properties of molds removed from a pattern or core box comprising applying a composition of the invention to the pattern or core box surface. A process for synthesizing a fluorotelomer or cotelomer from fluoroalkene monomers or comonomers is also provided.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 U.S.C. § 119 from U.S. Provisional Application Ser. No. 60/618,464 (filed Oct. 13, 2004) which is incorporated by reference herein for all purposes as if fully set forth.

FIELD OF THE INVENTION

This invention relates to a composition and to its use as an industrial lubricant, particularly as a mold release agent in the foundry industry.

BACKGROUND OF THE INVENTION

Many industrial operations require the use of release agents to reduce the tendency of a molded product to stick to the mold, or that of a tool, die or machine part to stick to the workpiece.

In foundry operations, metal parts are frequently made using “sand casting” methods wherein disposable foundry shapes, such as molds and cores, are fabricated with a mixture of sand and an organic or inorganic binder, sometimes referred to as a “foundry mix”. Molds and cores are produced by chemical or heat hardening of the mixture of sand and binder onto a pattern or core box. Sometimes a catalyst is used to cure the foundry mix more rapidly. A mold release agent, generally a polymer or a combination of polymers, is used to reduce or eliminate adhesion of a mold to a pattern or core box surface.

Various processes, such as, for example, the air-set or no-bake process, the carbon dioxide process, the cold box process, hot box processes, and similar mold manufacturing processes are well known to those skilled in the art. In these processes, sand and binder mixture is molded upon patterns or in core boxes. The patterns may be constructed from plastic, wood, or metal. Typical metals are aluminum and cast iron. Other materials may also be used. In the no-bake process, the sand/binder mixture, or foundry mix, contains a catalyst, so the mixture will cure rapidly without additional reagents. Heat may be added if desired in some processes to increase the cure rate. The foundry mix is shaped by compacting it in a pattern and allowing it to cure, so that the mix is self-supporting. The composition of the foundry mix, including any catalyst, must be such as to allow adequate worktime to allow shaping before the mixture hardens.

In the cold box method, a volatile curing catalyst (gaseous reagent) is passed through a shaped mixture of the foundry mix, usually in a core box, as opposed to a freestanding pattern mold. In this particular method of manufacture, the foundry mix must have adequate shelf life, meaning that it will not harden in the absence of a catalyst. The cure rate must be very rapid once the foundry mix is exposed to a catalyst.

Mold release agents are typically sprayed or brushed onto a pattern or core box surface periodically during pattern or core preparation. The mold release agent can be an emulsion or dispersion. If dispersed in a solvent, the solvent serves to wet the surface of a shape-determining mold, onto which the release agent is applied.

In the related art, silicone resins have been used as lubricants and release agents to prevent the pattern from sticking to the hardened foundry mixture. Silicones often do not, however, coat surfaces well when dispersed in a typical hydrocarbon solvent. The silicone resins are prone to bead or puddle on the surface to which they have been applied, thus preventing a thin, continuous film from being achieved.

Polytetrafluoroethylene (PTFE) dispersions are known, and can be used for treating the surfaces of various materials, such as metals, glass fibers, wood, rubber, and the like, to provide a protective, lubricating and anti-adhesive effect.

U.S. Pat. No. 6,596,829 discloses a mold release agent composition that enables numerous clean, lubricious releases of metal castings from hardened sand molds. The composition comprises a fluorotelomer comprising repeat units derived from a fluoroalkene, and optionally, a comonomer having an end group derived from a secondary alcohol or derivative thereof. The composition is applied to the surface of a substrate by conventional means such as spraying, dipping, wiping, brushing, or combinations of two or more thereof, for use as a release agent or lubricant.

It is highly desirable to reuse the same pattern or core box many times, to generate a number of molds from the same pattern or core box. Therefore, it is important for the pattern or core to be quickly and cleanly released from the finished molds with a minimum amount of release agent residue or build up on the pattern, and with minimal need to clean the pattern surface. One object of this invention is to provide an improved mold release agent composition that enables multiple release cycles, especially in cold box foundry processes. As used throughout the specification and claims, “mold release agent” is used to identify various composition embodiments of the invention having lubricant and abrasion resistant properties that facilitate the clean, low friction separation of a workpiece from a substrate, including patterns from cores and molds, castings from molds, cores and dies, and workpieces from tools and machine components. A workpiece is any object that is molded, stamped, drilled, ground, or otherwise worked upon by a manual or mechanical tool, mold, die, or the like.

SUMMARY OF THE INVENTION

This invention is directed to industrial lubricant and mold release agent compositions that facilitates separation of patterns and core boxes from foundry molds and cores, and castings from molds, and work pieces from dies, tools and machinery components.

This invention, in various embodiments, is directed to a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, and a silicone intermediate. In other embodiments, the invention is directed to said fluorotelomer repeat units, a silicone intermediate, and optionally a catalyst, a cross-linking agent, and/or a solvent.

In some embodiments the foregoing composition comprises a cotelomer containing an end group derived from a secondary alcohol or derivative thereof.

In some embodiments the foregoing composition comprises hydroxy-terminated poly alkylsiloxanes.

This invention is further directed to a method for improving the release properties of molds removed from a pattern or cores from a core box comprising applying a low friction coefficient composition of the invention to a surface of the pattern or core box.

This invention is also directed to processes for preparing fluorotelomer.

DETAILED DESCRIPTION OF THE INVENTION

The cross-linkable fluorotelomer can be based on any fluoroalkene repeating unit that can produce a fluorotelomer having the properties disclosed herein can be used. In one embodiment, the fluoroalkene monomer contains 2 to about 10, and in another, 2 to 3, carbon atoms. Examples of suitable fluoroalkenes include, but are not limited to, 1,1-difluoroethylene, 1,2-difluoroethylene, tetrafluoroethylene (TFE), 3,3,3-trifluoropropene, hexafluoropropylene (HFP), and combinations of two or more thereof. In a particular embodiment, the fluoroalkene is TFE.

In one embodiment, the fluorotelomers are homotelomers. In another embodiment, a cotelomer (copolymer) containing repeat units derived from a comonomer can also be produced. The comonomer is generally an ethylenically unsaturated compound, which can be fluorinated or perfluorinated. In an embodiment, the amount of repeat units derived from a comonomer can be in the range of from about 0.1 to about 10, and in another embodiment, 0.3 to 3.0 weight % of the copolymer.

Suitable comonomers include, but are not limited to, ethylene, propylene, butylene, decene, 1,1-difluoroethylene, 1,2-difluoroethylene, TFE, 3,3,3-trifluoropropene, HFP, and combinations of two or more thereof. The preferred comonomers are perfluorinated comonomers. Preferred comonomers are TFE, HFP, or combinations thereof.

As disclosed below, a hydrofluorocarbon can be used in a process for producing the fluorotelomer of the composition; a hydrofluorocarbon can also be incorporated into the fluorotelomer as an end group. Suitable hydrofluorocarbons include, but are not limited to, any of those disclosed in U.S. Pat. No. 5,310, 870, the disclosure of which is incorporated herein by reference. Examples of suitable hydrofluorocarbons include, but are not limited to, 2,3-dihydrodecafluoropentane, perfluorobutyl methyl ether, perfluorobutyl ethyl ether, 2,4-dihydrooctafluorobutane, 1,1,2,3,3,3-hexafluoropropyl methyl ether, 2-trifluoromethyl-2,3-dihydrononafluoropentane, 1,1,1,3,3-pentafluorobutane, or combinations thereof. These hydrofluorocarbons can be obtained commercially. For example, 2,3-dihydrodecafluoropentane is available from E. I. du Pont de Nemours and Company, Wilmington, Del. and perfluorobutyl methyl ether and perfluorobutyl ethyl ether are available from 3M Co., Minneapolis, Minn.

The fluorotelomer is cross-linkable, meaning; a cross-link feature has been designed into its structure. One example of a cross-linkable fluorotelomer has an end group derived from a secondary alcohol or derivative thereof, as disclosed in U.S. Pat. No. 6,596,829. The end group allows the fluorotelomer to crosslink with a compatible cross-linkable group on another fluorotelomer by means of a crosslinking agent. Suitable crosslinking agents include a tetraalkyl titanate having the formula of M(OR)₄ where M is titanium or zirconium and each R is independently an alkyl radical, a cycloalkyl radical, an aralkyl hydrocarbon radical, and combinations of two or more thereof in which each radical can contain, preferably, 2 to 12 carbon atoms per radical and each R can be the same or different. Suitable tetraalkyl titanates include, but are not limited to, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetra-n-butyl titanate, tetra-2-ethyl titanate, tetraoctyl titanate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetra-n-butyl zirconate, tetra-2-ethyl zirconate, tetraoctyl zirconate, and combinations of any two or more thereof. In particular embodiments, crosslinking agents include, but are not limited to, tetraisopropyl titanate and tetra n-butyl titanate, available from E. I. du Pont de Nemours and Company, Wilmington, Del. Crosslinked fluorotelomers generally have enhanced bonding, compared with non-crosslinked telomers, to the surface of a substrate, which can be made of wood, metal, plastic, rubber, stone, cement, glass, fiber, and combinations of two or more thereof. Cross-linking also achieves other desired properties such as hardness, rapid curing, and non-reactivity toward the pattern or core box substrate, thereby reducing or eliminating residues of release agent or foundry mix on said substrate.

In another embodiment, the invention discloses a process for preparing a fluorotelomer of the invention. In this process, a hydrofluorocarbon may be used to produce a fluorotelomer or to provide a moiety that can be incorporated into the fluorotelomer as an end group. The process, a telomerization, can be carried out at temperatures in the range of about 100° C. to about 200° C., preferably about 110° C. to about 180° C., and more preferably 120° C. to 160° C. at autogenous pressures. The pressure can range from about 100 to about 700 psig, preferably about 400 to about 600 psig, and more preferably about 500 psig. The preferred time period is about 1-6 hours, though it can be shorter or longer than this range. In a continuous flow reactor, the reaction can proceed for about 1-2 hours. A batch process can be preferably carried out at an autogenous pressure with temperatures in the range of about 125° C. to about 160° C. for about 4-6 hours. The molar ratio of hydrofluorocarbon to fluoroalkene can be in the range of from about 1:1 to about 10:1, preferably 2:1 to 8:1. Generally the higher the ratio, the lower the telomer molecular weight.

After the telomerization process, the fluorotelomer is generally dispersed as a suspension or emulsion in the hydrofluorocarbon and is recoverable in that form by filtration or other means. The dispersion can contain from about 5-20 weight % of the fluorotelomer, with dispersions of high molecular weight fluorotelomers falling at the low end of this range. If desired, the fluorotelomers can also be dispersed in other solvents such as isopropanol or in water as well.

The majority of the end groups of the fluorotelomer can be derived from any secondary alcohol or derivative thereof. A suitable secondary. alcohol or derivative thereof is one that is substantially soluble in a hydrofluorocarbon disclosed herein. In one particular embodiment, the secondary alcohols used are those having at least 4 to about 12 carbon atoms and an α-hydrogen. The end group can also be derived from a derivative of a secondary alcohol. The derivative of suitable secondary alcohol can include an ether or ester of a secondary alcohol or combinations thereof. Also suitable are combinations of a secondary alcohol, an ether thereof, and/or an ester thereof. Particular examples of suitable secondary alcohols of some embodiments include, but are not limited to, 2-propanol, 2-butanol, 2-pentanol, 2-hexanol, 2-heptanol, 2-butylacetate, cyclohexanol, 1-methoxy-2-propanol, 1-methoxy-3-butanol, 1-methoxy-2-pentanol, 1-methoxy-2-propanol acetate ester, and combinations of two or more thereof. In other embodiments, 2-butanol, 2-pentanol, or combinations thereof, are used.

The molar ratio of the repeat units derived from the fluoroalkene to the secondary alcohol or its derivative can be in the range of from about 18:1 to about 500:1, preferably about 120:1 to about 150:1. The molar ratio of the repeat units derived from the fluoroalkene to the hydrofluorocarbon can be in the range of from about 800:1 to about 2500: 1, preferably about 2000:1 to about 2400:1.

As disclosed below, a free radical initiator is generally used in producing the fluorotelomer. Generally, a minor amount of the free radical initiator can also be incorporated into the fluorotelomer. The amount incorporated generally is about the same as, or lower than, that of the hydrofluorocarbon.

The fluorotelomer can have or comprise a structure depicted as either H(CX₂)_(p)B_(q)D_(r) or a mixture of H(CX₂)_(p)B_(q) and H(CX₂)_(p)D_(r). In the formulae, X is H or F in which, in some embodiments, at least 80% is F, in other embodiments, at least 90% is F, and in still other embodiments, at least 99% is F; p is a number from about 36 to about 1500, preferred 60 to 600; B denotes any repeat units derived from a hydrofluorocarbon; q is a number from 0.02 to 0.4; D represents the end group derived from a secondary alcohol; and r is a number from 0.2 to 1.0.

A process that can be used to produce a fluorotelomer, such as the one disclosed above, comprises, consists essentially of, or consists of, combining a fluoroalkene, and optionally a comonomer, in a hydrofluorocarbon as solvent, with a free radical initiator and at least one secondary alcohol or derivative thereof. The fluorotelomer produced is the same as those disclosed above. The hydrofluorocarbon, secondary alcohol or derivative thereof, and comonomer are the same as those disclosed above.

Essentially, any free radical initiator can initiate reaction to produce the fluorotelomers of this invention in the presence of a hydrofluorocarbon, fluoroalkene, and secondary alcohol. Preferred free radical initiators are di-tertiary butyl peroxide, tertiary-butyl perbenzoate, tert-amyl peroctanoate, tert-amyl peroxy-2-ethylhexanoate, and azo initiators such as 1,1-azobis(cyanocyclohexane) and most preferred is di-tertiary butyl peroxide. The amount of free radical initiator used preferably falls within the range of 0.4 to 3.0, more preferably 0.7 to 2.5, by weight %, based on the weight of the fluoroalkene.

The amount of secondary alcohol present can be that which produces a fluorotelomer with a number average molecular weight in the range of from about 1,800 to 75,000 in one embodiment, and from about 3,000 to 30,000 in another. For example, the amount of secondary alcohol can be between about 0.1 to about 5, preferably about 0.3 and about 5, and preferably 2.5 to 4.0 mole %, based on the total number of moles of fluoroalkene.

The term, “silicone intermediate” refers to reactive silicones such as polyorganosiloxanes such as, for example, methoxy-terminated polyalkylsiloxanes, hydroxy-terminated polyorganosiloxane, and combinations of two or more thereof. Examples of polyorganosiloxanes include, but are not limited to, polydimethylsiloxanes, polymethylhydrogensiloxanes, polysilsesquioxanes, polytrimethylsiloxanes, polydimethylcyclosiloxanes, and combinations of two or more thereof which can be methoxy-terminated or hydroxy-terminated, or both.

A silicone intermediate may also be or comprise a volatile siloxane. The term “volatile siloxane” refers to a siloxane exhibiting volatility (the property of vaporizing readily under given temperature and pressure conditions) under the temperature and pressure of use. Typically, it can have an evaporation rate of more than 0.01 relative to n-butyl acetate which has an assigned value of 1. A volatile siloxane can have the formula of R¹(R¹ ₂SiO)_(x)SiR¹ ₃ or (R¹ ₂SiO)_(y) where each R¹ can be the same or different and can be an alkyl group, an alkoxy group, a phenyl group, a phenoxy group, or combinations of two or more thereof; having 1 to about 10 or 1 to about 8 carbon atoms per group. R¹ can also be a substituted alkyl group. For example, R¹ can be a methyl group or higher alkyl and can be substituted with a halogen, an amine, or other functional group. Subscript x can be a number from about 1 to about 20 or from about 1 to about 10 and y can be a number from about 3 to about 20 or from about 3 to about 10. Such volatile siloxanes can have a molecular weight in the range of from about 50 and to about 1,000 and a boiling point less than about 300° C.

The foregoing formulae can be modified to show the presence of siloxane in a release agent composition as follows: H—(CX₂)_(p)(Z)_(s)(CX₂)_(p).B_(q)D_(r)

wherein X, Z, B, D and p, q, r are as defined above. Z is:

wherein

p′ is independently a value within the parameters defined for p and s is an integer having a value in the range of from about 10 to about 13,500. Also, p and p′ can repeat, independently of themselves and each other, so that the telomer with siloxane additive represented by the foregoing formula can be characterized in a number of different ways, including, by way of the following illustrative, non-limiting examples: H—(CF₂)₆—(OSiO(R₂))₃—(CF₂)₄—(OSiO(R₂))₂—(CFH)₂—(CF₂)₈—(OSiO(R₂))₃—(CF₂)₁₂—(OSiO(R₂))—(CFH)—(CF₂)₄—(OSiO(R₂))₂—(CF₂)₉-D_(r) H—(CF₂)₄₂—(OsiO(R₂))—(CFH)—(CF₂)₆₈-D_(r) H—(CF₂)₆₀—(OsiO(R₂)—(CFH)—(CF₂)₆—(OsiO(R₂)—(CF₂)₁₆—(CH₂)—(CF₂)₁₁₂-D_(r)

The siloxane monomers represented by Z in the above formula in some embodiments provides a functional siloxane coating with optional organic or inorganic fillers that cures to a solid film upon application to the mold or pattern surface. The coatings of these embodiments cure to a solid film within about 10 minutes at temperatures of about 20° C. or higher. The coatings have a functional group on the siloxane monomers including hydroxyl, alkoxy, vinyl, hydrogen, amine, acrylate and methacrylate, and their derivatives. In some embodiments, the functional siloxane coating (“HTDS coating”) comprises, by weight percent:

-   -   30% to 60% hydroxy-terminated dimethyl siloxane;     -   30% to 75% inorganic or organic filler;     -   10% to 50% solvent or solvent blend;     -   7% to 13% titanium oxide; and     -   3% to 7% functional silane.         A functional silane is one that contains a functional group         compatible with polymerization, and that typically is         cross-linkable. A catalyst may optionally be used to accelerate         the cure process.

A solvent can be or comprise aromatic hydrocarbon, alkane, alcohol, ketone, ester, ether, inorganic solvent, water, and combinations of two or more thereof such as, for example, xylene, benzene, toluene, n-heptane, octane, cyclohexane, dodecane, methanol, ethanol, isopropyl alcohol, acetone, methyl ethyl ketone, dipropylene glycol, dipropylene glycol methyl ether, methylene chloride, methylene dichloride, ethylene dichloride, carbon tetrachloride, chloroform, perchloroethylene, ethyl acetate, tetrahydrofuran, dioxane, white spirit, mineral spirits, naphtha, and combinations of two or more thereof.

The release agent can further comprise additional components such as modified fumed silica, surfactants, fluoropolymers such as polytetrafluoroethylene, waxes, fatty acids such as stearic acid, fatty acid salts such as metal stearates, finely dispersed solids such as talc, emulsifiers, biocides, corrosion inhibitors. These are typically present in an amount of 0.01 to about 10 wt % of the total release agent composition.

Each component disclosed above can be present in the release agent composition of this invention in an effective amount sufficient to produce an effective mold release agent. The cross-linkable fluorotelomer is typically present in an amount of 0.1 to about 30 wt % of the total release agent composition. Typically, the silicone intermediate is present in an amount of 0.01 to about 5 wt % of the total release agent composition.

Any catalyst that can catalyze or enhance the curing of a coating composition disclosed above can be used herein. Examples include, but are not limited to, one or more zirconium compound, titanium compound, or combinations thereof. Examples of suitable catalysts include, but are not limited to, zirconium or titanium or those expressed by the formula M(OR²)₄ where M is zirconium or titanium and each R² is individually selected from an alkyl, cycloalkyl, alkaryl hydrocarbon radical containing from about 1 to about 30, or from about 2 to about 18, or from about 2 to about 12 carbon atoms per radical and each R² can be the same or different. Specific examples of catalysts include, but are not limited to, zirconium acetate, zirconium propionate, zirconium butyrate, zirconium hexanoate, zirconium 2-ethyl hexanoate, zirconium octanoate, tetraethyl zirconate, tetrapropyl zirconate, tetraisopropyl zirconate, tetrabutyl zirconate, titanium acetate, titanium propionate, titanium butyrate, titanium hexanoate, titanium 2-ethyl hexanoate, titanium octanoate, tetraethyl titanate, tetrapropyl titanate, tetraisopropyl titanate, tetrabutyl titanate, and combinations of two or more thereof. These catalysts are commercially available.

Other suitable catalysts include, without limitation, a Group VIII metal such as platinum, palladium, iron, rhodium, and nickel, or a complex thereof. Catalysts including, without limitation, zinc, tin and zirconium, and complexes thereof, are also suitable catalysts. Examples of still other suitable catalysts include, but are not limited to, dibutyltin diacetate, dibutyl dilaurate, zinc acetate, zinc octanoate, and combinations of two or more thereof. For example, dibutyltin diacetate can be used independently or in combination with a titanium compound.

Each of the catalysts disclosed above can be used in the composition in the range of from about 0.001 to about 10% relative to the total weight of the release agent composition.

The composition can be produced by any means known to one skilled in the art such as, for example, mixing each component disclosed above.

The mold release agent composition of this invention has excellent release qualities and allows for multiple reuses of the same pattern or core box to generate a large number of molds. The release agent can be used in various mold manufacturing processes, including air-set or no-bake process, the carbon dioxide process, and the cold box process. The mold can be made from any composition useful as a foundry mix. A typical mix comprises sand and a binder and, optionally, a catalyst. Other suitable aggregate materials can be used in combination with, or in place of, the sand in the foundry mix, such as for example, zircon, aluminosilicates and the like. Selection of the particular binder will generally depend on the mold manufacturing method and gaseous reagent employed, if the cold box method is used. Preferred combinations of gaseous reagent/binder are known to those skilled in the art.

The present invention provides a method to improve the release properties of molds removed from a pattern or core box comprising applying a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, a catalyst, and a solvent to the surface of the pattern or core box. While the discussion of mold-forming processes below presents cold box and no bake processes as examples, the selection of these illustrations is not intended to imply any limit to the processes to which compositions of the various embodiments of the invention are applicable.

In a cold box process, the method comprises (a) applying a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, a catalyst, and a solvent to the surface of the pattern or core box; (b) molding a foundry mix into the desired shape by shaping to the pattern or charging to the core box; and (c) contacting the foundry mix with a volatile curing agent. Examples of volatile curing agents would be secondary or tertiary amines or sulfur dioxide.

In a no bake process, the method comprises (a) applying a composition comprising a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, sufficient catalyst to enable curing, and a solvent to the surface of the pattern or core box; (b) molding a foundry mix comprising sand and a binder into the desired shape by shaping to the pattern or charging to the core box; and (c) curing the binder.

Also disclosed is a pattern or core box comprising a surface or a portion of the surface coated with a release agent a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene, a silicone intermediate, a catalyst, and a solvent. The substrate and composition are as disclosed above.

In the following Example 1 mold release compositions of the invention were made as described in the Example and recovered as described above. Comparative testing was done as described in Comparative Example 2.

EXAMPLES Example 1

A release agent was prepared from 0.740 lb of a cross-linkable polytetrafluoroethylene, 25% by weight in isopropanol, 0.167 lb of a silicone intermediate oil having hydroxyl functionality, silicone intermediate available from Dow Corning, Midland, Mich., 0.007 lb of tetraisopropyl titanate catalyst, available from E. I. du Pont de Nemours and Company; 0.100 lb of Dow Coming 200® Fluid, 0.65 CST, available from Dow Coming; 0.12 lb of reactive silicone oil, available from Dow Corning; 0.054 lb of Dow Coming 57 Additive, available from Dow Coming; a solvent mixture comprising 3.442 lb of a solvent blend TM3-65A, available from Chemical Solvents, Inc., Cleveland, OH, and 2.848 lb of dipropylene glycol monomethyl ether, available from Dow Chemical Company, Midland, Mich.

The release agent was prepared by dissolving the Dow Coming silicone intermediate and the reactive silicone oil in Dowanol DPM. The cross-linkable polytetrafluoroethylene and Dow Corning 200® Fluid were added after the Dow Corningsilicone intermediate was completely dissolved. TM3-65A was then added, followed by tetraisopropyl titanate catalyst to produce the release agent.

The release agent was tested using a Loramendi Cold Box core-making machine. The release agent was coated onto a core part by spraying. A molding composition was prepared from sand, and about 1 - 1.2% of a phenolic-urethane binder, Sigma Cure 7210/7500, available from HA International, LLP, Westmount, Ill. Sulfur dioxide (SO2) was used as the curing agent.

Several parts from those commonly used on the core-making machine were tested. The parts are listed in Table 1. In each test, 20-25 releases of the molded parts from the core boxes were achieved without sticking. TABLE 1 Part No. Designation Traxle A 689/690 B 710/711 C 147 D

Comparative Example 2

The testing was repeating using, a commercial PTFE-free, silicone-based release agent available from Ashland Specialty Chemicals, Dublin, Ohio in a side-by-side comparison with the release agent of Example 1. The same technique was used and the same amounts and method of applying the release agents were used as in Example 1. The release agent of Example 1 and the PTE-free silicone-based release agent had similar viscosities and specific gravities. The comparative results are provided in Table 2. TABLE 2 # of Releases PTFE-Free Release Total # Agent Example Release Agent Part of Runs Top Bottom Top Bottom A 3 5 3 10 10 B 10 10 10 15 15 C 16 5 5 10 10 D 16 3 3 15 15

Parts A, B, C, and D refer to different core parts in different shapes for the particular core-making machine. These parts are regarded as difficult cores to make, having a high tendency to stick to the molds. Because the tooling is being repeatedly used, the number of releases indicates the number of times the core was produced and did not stick to the core box. Due to machine malfunctions, the maximum number of releases that were able to be achieved was 15.

As shown by the data in the table, in all cases, the Example 1 release agent permitted a greater number of releases than the commercial release agent, based on a silicone alone in the Comparative Example. The fluorotelomer/silicone release agent of the invention enables the pattern to be used and reused more times than a conventional silicone-based release agent.

Example 3

A hydroxy-terminated polyalkylsiloxane moid release agent was compared to PTFE containing film coatings according to the following protocol:

Protocol: Proceeded to test a HTDS coating for abrasion resistance to bead blasting in a controlled environment. This formulation was compared to a formulation containing a PTFE based Dry Film to compare resistance to abrasion from bead blasting.

Product Application: Formulations were applied at room temperature to a small steel coupon made by Q-panel by spraying with an aerosol sprayer applying a uniform coating across the panel. The coating was allowed to cure for a period of time (5 minutes) before bead blasting was started.

Bead Blaster Equipment: Econoline, Grand Haven, Mich. 49417

-   -   Max. psi—120 psi     -   Min. psi—5 psi

The bead blaster is a self-contained unit delivering small beads through a high-pressure air nozzle capable of removing coatings/ rust/paint from a desired surface. The air pressure can be adjusted using a regulator connected to the bead blaster cabinet.

Size of beads used: Size D 50-70 US sieve

Pressure setting on regulator: 65 psi

Distance end of nozzle away from coated surface: 1- 1.5 inches.

Speed of movement with nozzle: slowly move nozzle right to left across plate.

The HTDS coating was tested in several solvent blends. The testing protocol included: (i) wet out on steel plates at room temperature; (ii) abrasion testing using bead blaster; and (iii) tape test for release. The results, with remarks, are set forth below. Formulation: A % B % C % D % E % IPA 65.0 62.5 60.0 65.0 62.5 MEK 32.5 32.5 28.0 32.0 32.0 HTDS Coating 2.5 5.0 9.0 2.8 5.3 9512/IPA 3.0 DC1-9770 0.2 0.2

Results: Wet Out Abrasion Tape Test Remarks A good very good very good Discoloration on plate; rust look B good very good very good less discoloration on plate C good no good no good did not cure on plate D good very good very good discoloration on plate E good very good very good slight discoloration on plate

The foregoing specification and examples illustrate various embodiments of release agent compositions that provide an abrasion resistant coating that facilitates the clean, low friction release of patterns from molds and cores, workpieces from dies, tools and machine components, and that have other industrial lubricant uses. Proper application of these compositions can provide enhanced life of patterns, dies, tools and machine components, reduced scrap and other waste, improved sand core and casting quality, and lower emissions of volatile materials that are detrimental to the environment. 

1. A method of easing the separation of a workpiece from a substrate comprising coating at least one of the workpiece and the substrate with a mold release agent selected from the group consisting essentially of: (a) a cross-linkable fluorotelomer comprising repeat units derived from a fluoroalkene monomer, and a silicone intermediate; (b) a cross-linkable fluorotelomer comprising repeat units derived from at least two fluoroalkene comonomers, and a silicone intermediate; (c) a hydroxy-terminated polyalkylsiloxane; and, optionally, a catalyst, cross-linking agent, and a solvent.
 2. The method of claim 1 wherein the cross-linkable fluorotelomer has an end group derived from a secondary alcohol or derivative thereof.
 3. The method of claim 1 further comprising a crosslinking agent having the general formula: M(OR¹)₄ wherein M is zirconium or titanium and each R¹ is, independently, an alkyl radical, a cycloalkyl radical, an aralkyl hydrocarbon radical, wherein each radical can contain from 2 to 12 carbon atoms per radical and each R¹ can be the same or different.
 4. The method of claim 1 further comprising a catalyst having the general formula: M(OR²)₄ wherein M is zirconium or titanium and each R² is, independently, an alkyl, cycloalkyl, alkaryl hydrocarbon radical, wherein each radical can contain from about 1 to about 30 carbon atoms per radical, and each R² can be the same or different.
 5. The method of claim 4 wherein each radical can contain from about 2 to about 18 carbon atoms per radical.
 6. The method of claim 5 wherein each radical can contain from about 2 to about 12 carbon atoms per radical.
 7. The method of claim 1 in which the mold release agent has the general formula: H—(CX₂)_(p)(Z)_(s)(CX₂)_(p′)—B_(q)D_(r) wherein X is H or F; B is any repeat unit derived from a hydrofluorocarbon; D is an end group derived from a secondary alcohol or —OH; Z has the formula:

each R, independently of each other, can be linear or branched alkyl, cycloalkyl, alkyl-substituted cycloalkyl, having from 1 to about 20 carbon atoms; p and p′ are each, independently, an integer having a value in the range of from about 0 to about 1500; q is a number from 0.02 to 0.4; r is a number from 0.2 to 1.0; and s an integer having a value in the range of from about 10 to about 13,500.
 8. The method of claim 7 wherein at least 80% of X is F.
 9. The method of claim 8 wherein at least 90% of X is F.
 10. The method of claim 9 wherein at least 99% of X is F.
 11. The method of claim 7 wherein p and p′ are each, independently, an integer having a value in the range of from about 36 to about
 1500. 12. The method of claim 1 1 wherein p and p′ are each, independently, an integer having a value in the range of from about 60 to about
 600. 13. The method of claim 7 wherein the mold release agent comprises, by weight percent: 30% to 60% hydroxy-terminated dimethyl siloxane; 30% to 75% inorganic or organic filler; 10% to 50% solvent or solvent blend; 7% to 13% titanium oxide; and 3% to 7% functional silane.
 14. The method of claim 1 wherein the fluoroalkene monomer or comonomer comprises 2 to about 10 carbon atoms.
 15. The method of claim 14 wherein the fluoroalkene monomer or comonomer comprises 2 to 3 carbon atoms.
 16. The method of claim 1 wherein the workpiece is selected from the group consisting essentially of cores, molds, and castings.
 17. The method of claim 16 wherein the workpiece is comprised of metal, glass fiber, wood, rubber, plastic, stone, silicate or aggregate.
 18. The method of claim 1 wherein the substrate is selected from the group consisting essentially of molds, core boxes, dies, tools, and machine components.
 19. The method of claim 18 wherein the substrate is comprised of metal, wood, glass fiber, rubber or plastic.
 20. A telomerization process for preparing a fluorotelomer comprising combining a fluoroalkene monomer and optionally a comonomer in a hydrofluorocarbon solvent with a free radical initiator and at least one secondary alcohol or derivative thereof.
 21. The process of claim 20 carried out at temperatures in the range of about 100° C. to about 200° C. at autogenous pressure.
 22. The process of claim 21 wherein the temperatures range from about 110° C. to about 180° C. at autogenous pressure.
 23. The process of claim 22 wherein the temperatures range from about 120° C. to about 160° C. at autogenous pressure.
 24. The process of claim 20 wherein the fluorotelomer has the general formula: H—(CX₂)_(p)B_(q)D_(r) or a mixture of: H—(CX₂)_(p)B_(q) and H—(CX₂)D_(r) wherein X, B, D, p, q, and r are as defined above.
 25. The process of claim 20 further comprising combining a silicone intermediate with the fluoroalkene monomer or optional comonomer.
 26. The process of claim 25 wherein the silicone intermediate has general formula 1 or 2: R¹(R¹ ₂SiO)_(x)SiR¹ ₃  1 (R¹ ₂SiO)_(y)  2 wherein each R¹ can be the same or different and can be alkyl, alkoxy, phenyl, phenoxy, or substituted derivatives of each of the foregoing, or combinations of two or more thereof; wherein each R¹ has from 1 to about 10 carbon atoms; x is an integer from 1 to about 20; and y is an integer from about 3 to about
 20. 27. The process of claim 26 wherein x is an integer from 1 to about
 10. 28. The process of claim 26 wherein y is an integer from about 3 to about
 10. 